PLEISTOCENE BISON SKELETON (BISON-BISON CF OCCIDENTALIS) FROM CLAYHURST-CROSSING, BRITISH-COLUMBIA

Remains of a large old male bison skeleton from a gravel pit near Clay hurst Crossing are tentatively referred to the extinct western bison ( Bison bison cf. occidentalis). It is the most complete late Pleistocen e ''medium-horned'' bison so far reported from Canada, and is therefor e described in detail. Four accelerator mass spectrometry (AMS) radioc arbon dates on bone from the specimen provide a weighted average age o f 10,500+/-90 yr BP, supporting an earlier suggestion that river terra ces in the mid-Peace area began developing before 10,000 years ago. Ev idently Bison bison antiquus occurred in southern Alberta about 11,000 years ago, and both it and Bison bison occidentalis occupied the Peac e River area shortly before 10,000 years ago. it is hypothesised that by at least 9700 BP, B. b. occidentalis had spread southern Alberta. T hese data suggest that biotic interchange between the former Beringian refugium and the southern interior Plains of North America occurred p rior to 10,500 years ago.